c-span: you mentioned columbia, and you s--talk a lot in your book about teachers college. what--what is it? what is it? what was it? and what impact has it had on education? >> guest: well, teachers college is where i took a lot of education courses, and--and my mentor--my personal mentor was the--the great professor at teachers college, lawrence kremmin. and he is, undoubtedly, the--the greatest historian o--of american education, and that's--it was with him that i studied and got my doctorate. c-span: why is he the greatest? >> guest: because he's just written incredible books. i mean, he's--he's written these very broad surveys of--of american education. he won the pulitzer prize. and he was a very rigorous, wonderful scholar and a great person to study with. i mean, he always made me feel so--i had to--he just had, again, this tremendous joie in what he was doing. he loved what he was doing, and he was constantly learning and sharing what he had learned. as a teacher, he was spectacular, and as a scholar, he was extremely painstaking. and being his student was both a p